The present invention relates to a voltage regulator of a generator, and more particularly to a voltage regulator suitable for a charge generator which charges a battery on an automobile.
As disclosed in Japanese Patent Laid-Open No. 55-37843(1980), for example, conventional voltage regulators of a generator effect voltage regulation in accordance with the temperature characteristics of a battery by means of the combination of a differential amplification circuit and a limiter circuit. However, since regulator of this kind uses two operational amplifiers, the number of devices is great, the chip area is great when the regulator is produced with a monolithic IC, and the cost of production becomes high.
And, as disclosed, for example, in U.S. Pat. No. 3,469,168, conventional voltage regulators include two systems of voltage detection circuits in order to prevent voltage control from failing if a voltage detection terminal of a battery, which is charged by a generator, comes off. However, since both systems are likely to have mutually different temperature characteristics, detection of an auxiliary voltage is effected preferentially at the time of normal generation, too, and the voltage of the battery can not be controlled accurately from time to time.